The composite system described above is subjected to a homogeneous deformation gradient \(\textbf {F}\) . The end-to-end vector of each representative strand at the reference configuration is shown by \(\textbf {R}^{(i)}_{0}\) . After deformation, the strand finds a new configuration, shown by the end-to-end vector \(\textbf {R}^{(i)}\) . The strands are assumed to be flexible chains formed by \(j\)  freely joined statistical segments. Taking into account the Langevin effect, the stored energy of each strand, stretched by \(\lambda _{e}\) , is [1]}
\(w^{(i)}(\lambda ,j)=jk_{B}T\bigg (\frac{\lambda _{e}\beta }{\sqrt{j}}+\ln \frac{\beta }{\sinh \beta } \bigg )+w^{(j)}_{0}\) 
